: Airport Link Speed, not getting 54Mbps


shane3547
Dec 20th, 2007, 11:01 AM
First off, I want to clerify that i do know what I'm talking about ... lol

I have a wireless connection at home for my MacBook Pro and my MacBook, the wireless router is also wired to my iMac. The connection speed does say 54Mbps connected, but I can't seem to get a transfer rate above 1.26MB/s when I should be getting something relatively close to 6.75MB/s

Math
----

54Mbps / 8 = Actual transfer rate in MB/s
ie. 54 / 8 = 6.75

Can someone please help me with this? I am using a Bell Speed Streem 6250 Wireless modem/router, even with my linksys router it does the same thing.

Here is a screen shot of the Network activity app

4068
And here is the actual speeds I'm getting fro iStat Menu
4069

monokitty
Dec 20th, 2007, 11:32 AM
The 54 MBps transfer speed is the theoretical maximum output that your wireless network is capable of transferring data at. Your Internet connection speed is at best 7 MBps through Bell. Therefore, despite your wireless network being able to transfer at higher speeds, it won't, because the source (your Internet connection) is capped at a much lower theoretical output.

However, you should be getting 54 Mbps transfer rates between all your Macs when transferring files and other data between them. But like I said above, your will not achieve these transfer rates between your Macs and your Internet connection.

shane3547
Dec 20th, 2007, 11:54 AM
Sorry, I should've been more explicate. Yes, I am just transfering from mac to mac. I understand the internet thing.


And the transfer rates are only from Mac to Mac.

EvanPitts
Dec 20th, 2007, 02:51 PM
Since WiFi is based on Ethernet... The 54Mb/s rating is for the total bandwidth of the connection. But Ethernet does not run very well if heavily loaded, and tends to "break" if more than 60% is used. As a rule of thumb, Ethernet is not very happy if loaded beyond 40%. Plus you have to factor in packet overhead, handshaking, and error correction. You can not simply divide by 8. However, I would expect your connection rate to be somewhere in the area of 3MB/s, factoring in everything.

You could be hindered by firewalling, which will "slow down" the apparent connection; as well as if you are using WPA or WEP encryption. You may also be hindered if the transmission strength of your devices is too high, as the signal may be clipped by the card, and hence, more packets would have to be resent because of errors. The final thing to consider is... Airport cards can be "locked" to run a B speeds, which is 11Mb/s (but your speeds indicate that you are running faster than that rate). Also, if you have multiple people connecting, the speed will be shared, more or less. Perhaps you have someone "dropping in" to your connection, and "borrowing" your network / internet... Just some thoughts on my part...

shane3547
Dec 20th, 2007, 03:46 PM
Since WiFi is based on Ethernet... The 54Mb/s rating is for the total bandwidth of the connection. But Ethernet does not run very well if heavily loaded, and tends to "break" if more than 60% is used. As a rule of thumb, Ethernet is not very happy if loaded beyond 40%. Plus you have to factor in packet overhead, handshaking, and error correction. You can not simply divide by 8. However, I would expect your connection rate to be somewhere in the area of 3MB/s, factoring in everything.

You could be hindered by firewalling, which will "slow down" the apparent connection; as well as if you are using WPA or WEP encryption. You may also be hindered if the transmission strength of your devices is too high, as the signal may be clipped by the card, and hence, more packets would have to be resent because of errors. The final thing to consider is... Airport cards can be "locked" to run a B speeds, which is 11Mb/s (but your speeds indicate that you are running faster than that rate). Also, if you have multiple people connecting, the speed will be shared, more or less. Perhaps you have someone "dropping in" to your connection, and "borrowing" your network / internet... Just some thoughts on my part...



WOW, thanks for the fountain of knowledge, I do have two wirelss connections, but only one active ... and the newtork is WPA encripted. with Mac Addressing only.

Todd
Dec 20th, 2007, 05:48 PM
Also consider the I/O capability of a laptop hard drive. They don't have the same capability as a full-sized desktop hard drive and that may limit the amount of data that can be sent or received. This is particularly true if your transfers are of many individual files versus a single large file.

EvanPitts
Dec 20th, 2007, 07:21 PM
Also consider the I/O capability of a laptop hard drive. They don't have the same capability as a full-sized desktop hard drive and that may limit the amount of data that can be sent or received. This is particularly true if your transfers are of many individual files versus a single large file.

Actually, they should have about the same throughput. My 2.5" 5400 RPM laptop drive is not much slower than my 3.5" 7200 RPM. The only constraint would be if the data was being transfered to either a Keychain or a USB external drive. USB would top out at about 1MB/s on single file transfer, slower yet if multiple files are bring transfered at the same time. I think the problem may be the WPA (or WEP) encryption, which would add to the time to assemble and disassemble packets; especially if the systems are firewalled, with no good way through the firewall. I would test the connection sans WPA and sans firewall, and see the ultimate speed it can attain. There has to be something peculiar slowing down the connection - and it just may be that the Airport is locking itself at "B" speeds, rather than at "G" speeds...

ron_da_voo
Dec 31st, 2007, 07:43 AM
FYI - 802.11n runs at 130 MB but any device on the network running g will force everything on the network to run at 54MB